The Texas shooter reportedly killed his wife's grandmother in the church massacre

From left are Christopher Rodriguez, Esmeralda Rodriguez, Mona Rodriguez, Jayanthony Hernandez, 12, and Juanita Rodriguez participate in a candlelight vigil for the victims of a fatal shooting at the First Baptist Church in Sutherland Springs, Texas, Sunday, Nov. 5, 2017.
AP Photo/Laura Skelding

The gunman behind the deadly church shooting in Sutherland Springs, Texas, reportedly killed his wife's grandmother in the massacre.

"The suspect's mother-in-law attended this church," Freeman Martin, the regional director of the Texas Department of Public Safety, said at a press conference Monday. Kelley's mother-in-law is Michelle Shields, White's daughter.

Martin confirmed that Shields had received "threatening text messages" from Kelley.

"There was a domestic situation going on within this family," Martin said, noting that he released the information to clarify that the shooting was not racially or religiously motivated.

Kelley married Danielle Lee Shields in Texas in 2014, according to The New York Times.

Kelley was previously married to a woman whom he lived with at Holloman Air Force Base in New Mexico, where he was serving in the military. While married to his first wife, Kelley was charged with "assault on his spouse and assault on their child," an Air Force spokesperson confirmed to The Times.

He was sentenced to confinement for 12 months and discharged from the military.